Our season at World Tea Expo will be packed with experiences, so Donna Fellman and I won’t have time to discuss the creaminess of oolongs—for that issue we recommend attending Thomas Shu’s* session “Cupping and Grading Oolong,” at 8am on Thursday June 16.**
So I thought I might discuss here why oolongs come across as creamy, despite their lack of any actual cream.
In 1993, Yuriko Nobumoto and her colleagues published a seminal paper*** on the aromatic components of pouchong, where they demonstrated that previously unidentified lactones were an essential component of the tea’s aroma. Previous to their work, Yamanishi and colleagues identified jasmine lactone, methyl jasmonate, linalool, linalool oxides, benzyl cyanide and indole as major aromas in oolong. However, these chemicals could not replicate the “characteristic sweet and milky aroma of pouchong tea.”
Via silica-gel chromatography, Nobumoto and her colleagues separated the tea’s components into 5 fractions and identified their aroma:
- #1: grassy-greenish [this is a pouchong, so lightly oxidized]
- #2: citrus-like
- #3: most significant pouchong tea aroma
- #4: sweet
- #5: unpleasant [that’s the indole fraction!—see blog of 5/13/16]
They then proceeded to analyze fraction #3, and found that it contained–in addition to geraniol, benzyl alcohol, and phenylethyl alcohol, all of which have a flowery odor–a total of 12 lactones, all of which have a fatty odor and creamy quality in the mouth.
Jasmin(e) lactone—found in oolongs, in jasmine and honeysuckle, and in Sri Lankan teas, too. Image from a great site for flowers and flower chemistry: http://wildflowerfinder.org.uk/Flowers/H/Honeysuckle/Honeysuckle.htm
It turns out that lactones contribute to the creaminess of cream as well.****
I’ve been trying to figure out why lactones have this quality…to no avail. Any thoughts?
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* Thomas Shu is the Vice President & Marketing Director of JT & Tea Inc. See http://www.worldteaexpo.com/wte16/Public/SpeakerDetails.aspx?nav=true&FromPage=Speakers.aspx&ContactID=1165588
** http://www.worldteaexpo.com/wte16/Public/SessionDetails.aspx?FromPage=Sessions.aspx&SessionID=1014417&SessionDateID=1000947
*** Y. Nobumoto, K. Kubota, A. Kobayashi. Lactones newly identified in the volatiles of pouchong-type semi-fermented tea. Bioscience, biotechnology, and biochemistry. 57:79-81, 1993.
**** Schlutt B, Moran N, Schieberle P, Hofmann T.Sensory-directed identification of creaminess-enhancing volatiles and semivolatiles in full-fat cream. J Agric Food Chem. 2007 Nov 14;55(23):9634-45. Epub 2007 Oct 13.
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